How to run a loop with isNaN

How would i make a loop where if a positive number isnt inputted, The question is asked again?

[Jan]

This sounds like a homework assignment. What have you tried so far? Which explicit problem to you have?

[Benjamin]

@Jan here is my code so far, i was trying to create a quadratic equation solver:

disp('Solving a quadratic polynonial (ax^2+bx+c), where a b and c are real numbers to 3 decimal places')
a = input ('What is your value for a?: '); %coefficient of x^2
a =~ NaN;
while isnan(a)
    a = input ('Please only enter a numerical value for a: ');
end

but my NaN loop isnt working correctly. I've just learnt about the while function and i was trying to implement a while loop that loops when anything other than a number is inputted

[Davide Masiello]

Your code seems fine, just remove the line

a =~ NaN;

and it works, meaning that if you input a = nan then it'll display the 'Please only enter a numerical value for a: ' message.

[Benjamin]

@Davide Masiello is there a way for this code to work if any letter is inputted as my value of a

Answer 1

[Davide Masiello]

disp('Solving a quadratic polynonial (ax^2+bx+c), where a b and c are real numbers to 3 decimal places')
a = input ('What is your value for a?: '); %coefficient of x^2
while ~isnumeric(a) || isnan(a)
a = input ('Please only enter a numerical value for a: ');
end

Solving a quadratic polynonial (ax^2+bx+c), where a b and c are real numbers to 3 decimal places

What is your value for a?: nan

Please only enter a numerical value for a: 'a'

Please only enter a numerical value for a: 2

>>

[Benjamin]

thankyou